Early unmanned landers used to explore the Moon in the 1960s, e.g., the U.S.S.R. Luna series and the U.S. Surveyor series, employed complex three-axis, body-stabilized systems, complex attitude and orbit control systems, complex thermal control systems, complex instrumentation systems, and complex landing systems. Such systems were very expensive. An objective of the present invention is to provide the capabilities of landers such as these at much lower cost, while adding new capabilities or enhanced capabilities at low cost.
The present invention incorporates some design features of the 1960s spin-stabilized Syncom communication satellite (the first successful geosynchronous telecommunication satellite) and subsequent spinning satellite designs that evolved during the following couple of decades, and adds some new capabilities and improves other capabilities. For example, in the present invention the spinning spacecraft body is outfitted with a landing system to convert it to a soft lander; furthermore, capability is added to the lander to enable its travel over the surface of the Moon or other solar-system body by “hopping”, giving the lander the new mobility capability which includes being able to avoid obstacles. Also, the lander's integral propulsion system, with axial thrusters used as a retro-rocket, reduce descent-phase propellant consumption and increase the propellant available for hopping, thereby increasing the travel range across the surface to 100s of meters, if not several kilometers
Development of this concept and the novel features described herein began in late 2007 by an experienced team of space-systems engineers—the Southern California Selene Group (SCSG), led by Dr. Harold A. Rosen—determined to win the Google Lunar X PRIZE (GLXP), announced in fall 2007. This as yet unclaimed prize is to be awarded to the first team that can successfully land a privately/commercially developed craft on the surface of the Moon while complying with a set of specific teaming, timeline, design and operational guidelines. During the course of several months from late 2007 to mid-2008 the SCSG team matured the spinning lander concept and made preparations for launch of the first proof-of-concept vehicle on a Space Exploration Technologies, Inc. (SpaceX) Falcon 1e rocket. In the first end-to-end point design, the Falcon 1e payload (or launch stack) consisted of a solid rocket motor kick stage for delivering the translunar injection burn, a multi-function interstage for facilitating initial system spinup and Earth-to-Moon cruise maneuvers, another smaller solid rocket motor for the braking maneuver at the Moon, and the spinning lander having hopping capabilities in accordance with the GLXP rules and the present invention. In this initial end-to-end concept both the interstage and the lander were outfitted with separate monopropellant (monoprop) hydrazine propulsion systems. Improved mission performance was demonstrated by the team's efforts on a more elegant end-to-end point design later in 2008 by replacing these monoprop systems and the smaller kick stage with a single, multi-function bipropellant (biprop) propulsion system integrated into the lander. This biprop design became the SCSG team's preferred approach for winning the GLXP.
The GLXP rules required that after landing on the surface of the Moon the landed craft—or another separate craft that landed with the main lander—traverse the surface an additional 500 meters. Most of the dozen or so system designs entered by the various competing GLXP teams involved landing one craft and then traversing with another, smaller rover-like craft. Since the spinning lander described by the present invention at landing has a functional and robust power supply, telecommunications system, propulsion system and instrumentation/sensor suite, not much more is needed for the roaming part of the GLXP mission. Thus, it is both mass- and cost-effective to roam the lander itself instead of providing for a separate roamer that would need to duplicate the functions of these systems. The cost of roaming in this approach is simply the additional liquid propellant needed for the roaming hops. In the GLXP point designs worked out by the SCSG team, approximately half of propellant loaded into the lander would be available for roaming after a nominal landing. Hopping rather than roving or crawling enables traveling across the surface easily, because the presence of obstacles in the path between waypoints can be avoided by a hopping roamer that can leap over them in a single bound.